About SES DKIM records

SES requires 3 CNAME records for DKIM. When sending email only one of the DKIM keys are active and used for sending messages SES will rotate the key in use for you

https://docs.aws.amazon.com/ses/latest/dg/send-email-authentication-dkim-easy.html#send-email-authentication-dkim-easy-setup-domain

If you would like to use just one record you can use BYODKIM and create just one record https://docs.aws.amazon.com/ses/latest/dg/send-email-authentication-dkim-bring-your-own.html